A method for removing cyanide-containing waste gas

Abstract

The invention relates to a method for removing cyanogen-containing waste gas. A catalytic removal reaction is carried out on cyanogen-containing waste gas by using a transition metal supported mesoporous molecular sieve catalyst, wherein a mesoporous molecular sieve carrier is MCM-41, MCM-48, SBA-15, SBA-16, KIT-5 or KIT-6; a transition metal active component is one or more of Cu, Co, Cr, Mn, Ag or V; and the mass ratio of the carrier to the transition metal component is 1;(0.02-0.07). The method comprises the following steps: placing the molecular sieve catalyst in a fixed bed quartz reactor; introducing a mixed gas of the cyanogens-containing waste gas, oxygen and nitrogen into a reaction furnace at the space speed of 17000-24000h<-1> at normal pressure under the condition that the temperature of the reaction furnace is raised to 350-650 DEG; and removing the waste gas through catalytic combustion. The prepared catalyst is used for inspecting the selective catalytic combustion of the cyanogens-containing waste gas, has the characteristics of low combustion starting temperature and high N2 selectivity, and is suitable for efficient purification of the cyanogen-containing waste gas.

Description

technical field [0001] The invention belongs to a method for removing cyanide-containing waste gas, and specifically relates to a method for removing cyanide-containing waste gas by using a transition metal-loaded mesoporous molecular sieve as a catalyst through a catalytic combustion method, which can be used for removing hydrogen cyanide , acrylonitrile and CH 3 CN (acetonitrile) and other cyanide-containing waste gas. Background technique [0002] At present, there are three main methods for removing cyanide-containing waste gas: absorption method, adsorption method and combustion method. The catalytic combustion method in the combustion method is to react the cyanide-containing waste gas with oxygen under the action of a catalyst to convert it into nitrogen, nitrogen dioxide and water. Because the catalytic combustion method has the advantages of low ignition temperature, no secondary pollution, reusable waste heat, convenient operation and management, and low operatin...

AI Technical Summary

Problems solved by technology

[0003] The key technology of the catalytic combustion method is to develop high-efficiency catalysts for different processes. At present, the catalysts used to remove cyanide-containing waste gas are mainly noble metal catalysts. For example, patents CN1404900A, CN1404904A and CN1404905A disclose methods for removing hydrogen cyanide waste gas. The catalyst used is mainly single or multiple proportioning metals of platinum, palladium and rhodium, but the price of precious metals is expensive, the number of active centers is small, and the utilization rate of precious metals is low; what patent CN1416950A uses is a platinum metal catalyst loaded with alumina as a carrier , although the utilization rate of the metal is improved and the number of active centers is increased, the high price also limits the application in this field due to the lack of precious metal resources.

In order to solve the above problems, the patent CN1462652A proposes to use alumina as a carrier to support copper metal catalyst, and hydrogen cyanide, ammonia, tar, air and nitrogen as reaction raw materials, at a space velocity of 1000-50000h -1 , the hydrogen cyanide waste gas is removed at a temperature of 100-300°C. This method reduces the cost of the catalyst, but due to the low specific surface area of ​​the alumina carrier, the dispersion of the active components is poor, and the catalytic activity is affected to a certain extent. The lowest conversion rates of hydrogen, ammonia and tar are about 84%, 68% and 92% respectively, and the introduction of ammonia and tar into the raw materials of the reaction process has certain pollution

[0004] In addition, in the above-mentioned prior art, most of the cyanide-containing waste gas removed is aimed at hydrogen cyanide and acrylonitrile waste gas, and for acetonitrile (CH 3 CN) exhaust gas removal, due to the CN-functional group of acetonitrile and the methyl CH 3 The chemical bonds between - are compared with hydrogen cyanide structure (CN-functional group is connected with hydrogen group H-), acrylonitrile structure (CN-functional group is connected with vinyl CH 2 CH-connection) is more stable, and the chemical bond is difficult to break. Experiments have proved that a small part of acetonitrile can be removed at least at 700 ° C under non-catalytic conditions. Therefore, compared with hydrogen cyanide and acrylonitrile, the removal conditions of acetonitrile require Higher, there are few literatures on the removal of acetonitrile

[0005] Mesoporous molecular sieve is a new type of material with a pore size between 2-50nm and regular pore distribution. Its advantages are large specific surface area, regular pore structure, good stability, and mesoporous molecular sieve catalyst loaded with transition metals. It has been applied to many catalytic reaction processes, showing excellent reactivity and high selectivity, but for the catalytic process of removing cyanide-containing waste gas, especially for the removal of CH 3 The application of molecular sieve catalysts for CN exhaust gas has not been reported

Images